In recent years, exfoliated graphite having a small number of stacked graphene layers has attracted attention. A method for producing exfoliated graphite using GIC is known as a method for producing exfoliated graphite. In this method, an alkali metal is intercalated between the graphene layers of graphite. Then, graphite is exfoliated by ultrasonic treatment, heat treatment, or the like.
Non Patent Literature 1 to be described below describes the reactivity of an alkali metal-GIC prepared by intercalating K or the like between graphene layers as an alkali metal. Non Patent Literature 1 describes that when graphite is brought into contact with an alkali metal vapor to obtain an alkali metal-GIC and then the alkali metal-GIC is brought into contact with air, the structure of the alkali metal-GIC changes. That is, it is shown that, in addition to a peak of the structure of stage 1 represented by KC8, a peak of stage 2 represented by KC24 and a peak of stage 3 appear on an XRD spectrum.
On the other hand, Patent Literature 1 to be described below discloses a method for producing a graphene solution which facilitates the processing of a graphene-like carbon material. In this method for producing a graphene solution, graphite is first reduced with an alkali metal such as K, and the alkali metal is intercalated between graphene layers. Then, GIC is brought into contact with a polar aprotic solvent. Thereby, a graphene solution in which GIC is dissolved in the polar aprotic solvent is obtained.